问题描述
在使用Azure上的存储服务 Storage Account 的时候，有时需要代替 它原本提供的域名进行访问，比如默认的域名为：mystorageaccount.blob.core.chinacloudapi.cn， 想转变为 myservice.file.com 。
如果使用App Service作为反向代理，我们现在有如下三个疑问：
第一：如何来设置方向代理呢？
第二：是否还能成功访问Storage Account服务呢？
第三：.NET Storage Account SDK中如何使用自定义的域名连接服务呢？
问题解答
根据问题中的三个疑问，我们一一测试及解答。
第一问，在App Service服务中如何实现反向代理呢？
参考之前的文章：
- 【Azure 应用服务】在App Service for Windows中实现反向代理 : https://www.cnblogs.com/lulight/p/17120713.html
- 【应用服务 App Service】 App Service Rewrite 实例 - 反向代理转发功能 : https://www.cnblogs.com/lulight/p/13875393.html
第一步：applicationhost.xdt 启用IIS代理功能
选择一个 Windows 平台的App Service，进入Kudu站点，在 Site 目录下创建 applicationhost.xdt 文件并复制下面的内容
<?xml version="1.0"?><configuration xmlns:xdt=http://schemas.microsoft.com/XML-Document-Transform><system.webServer><proxy xdt:Transform="InsertIfMissing" enabled="true" preserveHostHeader="false" reverseRewriteHostInResponseHeaders="false" /></system.webServer> </configuration>
xdt:Transform="InsertIfMissing"表示如果代理配置不存在，则插入这一配置。enabled="true"表示启用代理功能。preserveHostHeader="false"表示不保留原始请求的主机头信息。reverseRewriteHostInResponseHeaders="false"表示在响应头中不反向重写主机头信息。
第二步：web.config 配置 rewrite rule
第一步完成后，点击 WWWROOT 目录，添加新文件 web.config 并复制下面的内容
<configuration> <system.webServer> <rewrite> <rules> <rule name="root" stopProcessing="true"> <match url="^/?(.*)" /> <action type="Rewrite" url="https://<stroage account name>.blob.core.chinacloudapi.cn/{R:1}" /> </rule> <!-- 需要对根目录的请求进行反向代理，否则对POST/PUT等操作会报错404无法找到Blob Containers --><!-- <rule name="sa" stopProcessing="true"> --><!-- <match url="^sa/?(.*)" /> --><!-- <action type="Rewrite" url="https://<storage account name>.blob.core.chinacloudapi.cn/{R:1}" /> --><!-- </rule> --></rules> </rewrite> </system.webServer> </configuration>
第二问，是否还能成功访问Storage Account服务呢？
完成App Service的反向代理配置后，重启服务。然后进入Storage Account的共享访问签名生成页面。
第一步：使用原生的 SAS URL访问Blob文件
原生的URL为：
https://< your storage account >.blob.core.chinacloudapi.cn/<your container name>/<filename>.txt?
sp=r&st=2025-03-01T13:16:47Z&se=2025-03-01T21:16:47Z&spr=https&sv=2022-11-02&sr=b&sig=xxxx%xxxx%3D
第二步：用App Service的域名替换原生的Storage Account域名访问
替换后的URL为：
https://<your app service custom domain name>.chinacloudsites.cn/<your container name>/<filename>.txt?
sp=r&st=2025-03-01T13:16:47Z&se=2025-03-01T21:16:47Z&spr=https&sv=2022-11-02&sr=b&sig=xxxx%xxxx%3D
测试验证，两种域名均可访问。证明，反向代理配置成功！
第三问：.NET Storage Account SDK中如何使用自定义的域名连接服务呢？
是的，在默认的.NET Storage Account SDK中，默认使用的是连接字符串(Connection String)。
DefaultEndpointsProtocol=https;AccountName=storagesample;AccountKey=<account-key>;EndpointSuffix=core.chinacloudapi.cn
以上的格式，无法修改EndpointSuffix为自定义的域名。所以，使用连接字符串肯定是不可以的。
代替的方案就是使用共享访问签名(SAS URL)来初始化BlobServiceClient对象。
参考“快速入门：适用于 .NET 的 Azure Blob 存储客户端库” 文章中的代码，只需要修改初始化 Blob Service Client对象的那一段代码就可以，改动量非常小。
//Use SAS URL string accountsas = "https://<the app gateway domain name>/?sv=2022-11-02&ss=bfqt&srt=sco&sp=rwdlacupitfx&se=2025-02-28T13:55:27Z&st=2025-02-28T05:55:27Z&spr=https&sig=PxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxD";Uri sasuri = new Uri(accountsas); // Create a BlobServiceClient object which will be used to create a container client BlobServiceClient blobServiceClient = new BlobServiceClient(sasuri);
注意：代码中使用的共享访问签名SAS URL是Storage Account级别的，不能使用第二问中的一个blob文件的SAS URL，否则会出现权限不够报错。
运行效果展示：
参考资料
- 在App Service for Windows中实现反向代理 : https://www.cnblogs.com/lulight/p/17120713.html
- App Service Rewrite 实例 - 反向代理转发功能 : https://www.cnblogs.com/lulight/p/13875393.html
- BlobServiceClient 构造函数 : https://learn.microsoft.com/zh-cn/dotnet/api/azure.storage.blobs.blobserviceclient.-ctor?view=azure-dotnet#azure-storage-blobs-blobserviceclient-ctor(system-uri-azure-storage-storagesharedkeycredential-azure-storage-blobs-blobclientoptions)
- 快速入门：适用于 .NET 的 Azure Blob 存储客户端库 ： https://docs.azure.cn/zh-cn/storage/blobs/storage-quickstart-blobs-dotnet?tabs=visual-studio%2Cconnection-string%2Croles-azure-portal%2Csign-in-azure-cli%2Cidentity-visual-studio
附录：如果在设置反向代理的时候，没有从根目录跳转，就会遇见如下错误：
The specified container does not exist.
RequestId:000000
Time:2025-02-28T05:57:16.7457335Z
Status: 404 (The specified container does not exist.)
ErrorCode: ContainerNotFoundContent:
<?xml version="1.0" encoding="utf-8"?><Error><Code>ContainerNotFound</Code><Message>The specified container does not exist. RequestId:00000 Time:2025-02-28T05:57:16.7457335Z</Message></Error>Headers:
Date: Fri, 28 Feb 2025 05:57:16 GMT
Server: Windows-Azure-Blob/1.0,Microsoft-HTTPAPI/2.0
Set-Cookie: REDACTED
x-ms-request-id: e000000
x-ms-client-request-id: 5e
x-ms-version: 2020-08-04
x-ms-error-code: ContainerNotFound
X-Powered-By: REDACTED
Content-Length: 225
Content-Type: application/xml
附录：完整代码参考
using Azure; using Azure.Identity; using Azure.Storage.Blobs; using Azure.Storage.Blobs.Models; using System; using System.IO; using System.Text; using System.Threading.Tasks;namespace BlobQuickstartV12 {class Program{static async Task Main(string[] args){Console.WriteLine("Hello World!");Console.WriteLine("Azure Blob storage v12 - .NET quickstart sample\n");// Retrieve the connection string for use with the application. The storage// connection string is stored in an environment variable on the machine// running the application called AZURE_STORAGE_CONNECTION_STRING. If the// environment variable is created after the application is launched in a// console or with Visual Studio, the shell or application needs to be closed// and reloaded to take the environment variable into account.//string connectionString = "Connection String";string accountsas = " SAS URL ";Uri sasuri = new Uri(accountsas);// Create a BlobServiceClient object which will be used to create a container clientBlobServiceClient blobServiceClient = new BlobServiceClient(sasuri);//Create a unique name for the containerstring containerName = "lbllmpackage";// "quickstartblobs" + Guid.NewGuid().ToString();// Create the container and return a container client objectBlobContainerClient containerClient = blobServiceClient.GetBlobContainerClient(containerName);Console.WriteLine("Listing blobs...");// List all blobs in the containerawait foreach (BlobItem blobItem in containerClient.GetBlobsAsync()){try{Console.WriteLine("\t" + blobItem.Name);BlobClient bclient = containerClient.GetBlobClient(blobItem.Name);await bclient.CreateSnapshotAsync();}catch (Exception ex){Console.WriteLine(ex.Message);}}var prp = containerClient.GetProperties();// Create a local file in the ./data/ directory for uploading and downloadingstring localPath = @".\data\";string fileName = "quickstart" + Guid.NewGuid().ToString() + ".txt";string localFilePath = Path.Combine(localPath, fileName);// Write text to the fileawait File.WriteAllTextAsync(localFilePath, "Hello, World! the message from .net");// Get a reference to a blobBlobClient blobClient = containerClient.GetBlobClient("/test/" + fileName);Console.WriteLine("Uploading to Blob storage as blob:\n\t {0}\n", blobClient.Uri);// Open the file and upload its datausing FileStream uploadFileStream = File.OpenRead(localFilePath);await blobClient.UploadAsync(uploadFileStream, true);uploadFileStream.Close();Console.WriteLine("Listing blobs...");// List all blobs in the containerawait foreach (BlobItem blobItem in containerClient.GetBlobsAsync()){Console.WriteLine("\t" + blobItem.Name);}// Download the blob to a local file// Append the string "DOWNLOADED" before the .txt extension // so you can compare the files in the data directorystring downloadFilePath = localFilePath.Replace(".txt", "DOWNLOADED.txt");Console.WriteLine("\nDownloading blob to\n\t{0}\n", downloadFilePath);// Download the blob's contents and save it to a fileBlobDownloadInfo download = await blobClient.DownloadAsync();using (FileStream downloadFileStream = File.OpenWrite(downloadFilePath)){await download.Content.CopyToAsync(downloadFileStream);downloadFileStream.Close();}}} }
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